Abstract: In P2P file-sharing systems, many strategic frauds often occur. However, the existing trust model can not completely eliminate the risk in transactions. By combining both local and global trust mechanisms, this article proposed a new calculation expression of reputation according to records shared between peers. Furthermore, it put forward reputation-driven group organization management and peer-search algorithm. The simulation results show that this reputationdriven mechanism can find the peer with the high value of reputation as the trading partner and can effectively reduce the risk in transactions when the system is confronted with attacks from malicious conspiracy peers and malicious peers with trading strategies.

Key words: Peer to Peer(P2P) network, file-sharing, reputation, group, searching

摘要： 在P2P文件共享系统中，常会出现许多有策略的欺骗行为，而现有的信任模型并不能完全消除交易的风险。综合局部信任机制和全局信任机制，根据节点间相关的共享记录数据提出一种新的信誉计算方法，并进一步提出受信誉驱动的分组组织管理和节点搜索算法。仿真结果证明该信誉驱动机制能搜索到信誉值高的节点作为交易对象,并能有效降低系统面对合谋恶意节点和具有交易策略的恶意节点攻击时的交易风险。

关键词: P2P网络, 文件共享, 信誉, 分组, 搜索